Emphasizing with 是…的

Structure 是 + (when/where/how) + Verb + 的

When an action ALREADY happened and what matters isn’t WHETHER it happened but WHEN, WHERE or HOW, you frame that detail with 是 … 的: 我是昨天来的 = "I came YESTERDAY" (the focus is on "yesterday"). 是 goes before the highlighted detail and 的 closes the sentence. It differs from 了 (which only reports that the action took place).

Examples

我wǒ是shì昨zuó天tiān来lái的de。
I came yesterday.
你nǐ是shì在zài哪nǎ儿r学xué的de中zhōng文wén？
Where did you learn Chinese?
他tā是shì坐zuò飞fēi机jī来lái的de。
He came by plane.

Levels are indicative: they follow the standard Chinese Grammar Wiki (AllSet Learning) progression, not an official HSK 3.0 mapping. We never assign levels by eye.

This point and the other 370, with audio on every example, inside Wanyu.